1. Field of the Invention
The present invention relates, in general, to a sheet handling device and, more particularly, to an electrically powered rotary collator which collates sheets.
Rotary collators use a rotating drum with radially extending partitions which divide the drum into radially extending bins. Each successive bin may be loaded with a plurality of sheets of successive pages of a booklet to be collated. Some of the bins may be empty. As the drum rotates, the pile of sheets in each loaded bin is held against its bin by a sheet clamp except at a sheet ejecting position or a region thereof when the stack of sheets must be released or unclamped so that the top sheet can be withdrawn from the bin. A sheet from each of the loaded bins is withdrawn and the sheets are assembled together in sequence so that they may be stapled or otherwise bound together.
After each bin passes the sheet ejecting position, the sheet clamp is operated to clamping position by an activating device that uses a toggle structure. In known machines, the sheet clamp held against each bin is released when the bin reaches its ejecting position and is clamped again soon after the bin moves beyond its ejecting position. In these previous systems, the clamping/unclamping procedure takes place on each bin irrespective of whether sheets are loaded in the particular bin in question.
The clamping springs used are strong enough to hold thick stacks of sheets against the partition side. Consequently, the cumulative effect of the noise generated by released sheet clamps slamming shut against empty bins is significant in these previous systems. In addition, individual elements of the mechanism are subject to wear, despite the fact that their functions are not always required.
2. Description of the Prior Art
U.S. Pat. No. 2,936,168 teaches the use of a rotating drum with radially extending partitions. No provision is made therein for programmably disabling sheet clamps which are not required during the collating operation. U.S. Pat. No. 3,970,297 shows and describes apparatus for withdrawing a single top sheet from each bin as the bin reaches the ejecting position in the collator cycle. The sheet withdrawing invention described in the above patent can be used in conjunction with the present invention, as hereinafter disclosed.
U.S. Pat. No. 3,796,422 teaches the use of a sheet clamp release activating device which uses a toggle structure. The activating device of that invention is actuated each time a bin approaches its ejecting position, regardless of whether the bin contains sheets. The resulting objectionable noise and wear of parts are significant in that system.
Controlling discs have long been used in various fields to complete one or more electrical circuits at specified times for predetermined intervals of time, as shown and described, for example, in U.S. Pat. Nos. 2,623,132 and 2,866,021. The operation of these discs, however, has been dependent on time, per se, but independent of any other system functions. As such, these inventions are not suitable for application in the variable-speed collator art, since time alone is not necessary and sufficient to control an electrical circuit associated with a manual or automatic collator.
U.S. Pat. No. 4,003,566 teaches the use of a controlling disc, similar to that used in the present invention. Collating systems in the class represented by the above patent generally activate each sheet clamp once every collating cycle. Electrical switches are repeatedly made and broken in those systems. Associated sheet clamps are consequently also repeatedly clamped and released. With prior programming means the switch bounces. This bouncing severely limits the life of the switch and solenoid by causing excessive chatter and wear.
Accordingly, the present invention now reduces the noise associated with sheet clamping operations of a rotary collator by eliminating the switch bouncing between successively selected pins in the programming means. Only those sheet clamps which must be released, or opened, during the eject cycle of their corresponding bins are specified in advance. Certain bins which are either empty or loaded with unwanted sheets now remain intact in a closed position at all times during the collating cycle. The life expectancy of mechanical elements is extended by reducing wear on those clamp mechanisms associated with empty or unused bins. The total amount of energy expended for a normal collating project is also reduced by the present invention by activating less than all mechanisms during each sheet ejecting cycle.